Vehicle transmission control



Feb. 17, 1953 E. c. MORAE 2,

VEHICLE TRANSMISSION CONTROL dri inal Filed Nov. 17, 1949 s Sheets-Sheet1 E. C. McRA E INVENTOR.

Km BY A TTO RNEVS Feb. 17, 1953 E. c. M RAE 2,628,510

VEHICLE TRANSMISSION CONTROL Original Filed Nov. 1'7, 1949 5Sheets-Sheet 2 CARR/ER -DR/ VE N C ARR/ER *0 75 N DR/ VER 6' TA TDNARYLOW-23 7O /.0 RAT/O REVERSE 2.0 T0 LORAT/O m; 1115-... v m fll CARRIER0m DRIVE Q 3 TA TIO NARY MHFRMED/ATEIJ? 701,0 RATIO 5, C. M RA EINVENTOR.

0 BY 07d). M

A TTOPNEVS Feb. 17, 1953 E. c. MCRAE 2,628,510

VEHICLE TRANSMISSION CONTROL Original Filed Nov. 17, 1949 5 Sheets-SheetIO 5'! LOW 6! HE-11E: I 6O ECMCRAE IN VEN TOR.

TFI-E B BY swim ATTORNEYS Feb. 17, 1953 E. c. M RAE 2,528,510

VEHICLE TRANSMISSION CONTROL Original Filed Nov. 17, 1949 5'Sheets-Sheet 4 mil,

E. C. M RA E INVENTQR.

A T TO RNEVS Feb. 17, I953 E. c. MG'RAE 2,628,510

VEHICLE TRANSMISSION CONTROL Original Filed Nov. 17, 1949 5 Sheets-Sheet5 ATTORNEYS ?atented Feb. 17, 1953 Ford Motor Company, Dearborn, Mich, acorporation ofDelaware ENT OFFICE- Original application November 17,1949, Serial No.

1950, Serial No. 165,725

(Cl. 7 i752) 2 Claims.

This application. is. a division of my co-pending application Serial No.127,849, filed. November 1'7, 1949, for Vehicle. Transmission, nowPatent No. 2,514,963.

The object of my invention is to provide a vehicle transmission of aplanetary gear type in which each of the various speed ratios iseffected by the application of a single. band brake or clutch. Myimproved transmission provides one reverse and two forward reduced gearratios together with a direct drive coupling.

A further object of. my invention is to provide a vehicle transmissionhaving three forward speeds and one reverse speed and in which a singleelement is used as the driving member for eii ecting all of such speedsand another single element is used as the. driven member for all of suchspeeds. The. advantage. of this construction is that it becomesunnecessary to clutch or declutch either the driving element or thedriven element for efiecting' any of the speeds of the transmission. Theapplicantis aware that many transmissions having this characteristichave been designed, but believes that. all three speed transmissions ofthis. type require the. simultaneous application of one clutchingelementwith the release of another element. This requires delicatesynchronization whichis avoided in the unit shown.

The applicants transmissionis unique in that a single driving elementand a single driven element are coupled in such manner as to producethree forward speeds and. one. reverse speed by the application of asingle braking element for each speed and wherein the direct drivecoupling is effected without disengaging. the intermediate speedcoupling. The shift from intermediate speed to direct drive maytherefore be made under power and without the necessityof synchronizingthe two clutch members.

A further object of my invention is to provide a transmission throughwhich. the. engine of'the vehicle may be cranked by the. car even whenthe transmission is in neutral. position. The advantage of thisconstruction. is thatwhen it is.

desired to start the engine by pushing, the. car, it. is unnecessary toengage any of the bands or clutches. Inasmuch as the clutches'inautomatic transmissions are usually hydraulically operated, it hasheretofore been necessary to provide a separate source of power, drivenby the wheels of the vehicle, to apply thebandsv when the car is to bestarted by pushing. With my improved auxiliary source of power.

Divided and this application June 2,

A further object of my invention is to provide a transmission in whichthe clutch which is engaged to effect the direct drive speed transmitsonly about A; engine torque. This is particularly advantageous in thatwhere such clutch is hydraulically operated, it permits the use of lowoil pressure for the operation of the clutch.

A further object of my invention is to provide a transmission having.several bands therein which are actuated by individual cylinder andpiston assemblies and wherein all of these cylinder and pistonassemblies are mounted upon a plate which is readily detachable from thebottom of the transmission. This construction permits the assembly ofthe piston and cylinder units separate from the transmission.

With these and other objects. in view, my invention consists of thearrangement, construction and combination of the various parts of myimproved device, as described in this specification, claimed in myclaims, and illustrated in the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view through my improvedtransmission.

Figure 2 is a diagrammatic View showing the gearing employed to effectthe low speed gear ratio.

Figure 3 is a diagrammatic view showing. the gearing employed to effectthe reverse speed gear ratio.

Figure 4 is a diagrammatic view showing the gearing employed to effectthe intermediate speed gear ratio.

Figure 5 is a sectional view, taken. upon the line 55 of Figure 1.

Figure 6 is a sectional view, taken upon the line E6 of Figure 1.

Figure 7 is a view lookin 'up at the. underside of the transmission,illustrating the quickly detachable plate which supports all of theoperating cylinders. I

Figure 8 is a side elevation of the transmission showing the solenoidoperated valve b1ock.

Figure 9 is a sectional view, taken upon the line 9-9 of Figure 8.

Figure 10 is a sectional view, taken upon line Hll0 of Figure 1.

Figure 11 is a sectional view, taken upon line H-H of Figure 1.

Figure 12 is a chart showing which bandsor clutches are engaged for eachof the gear ratios provided in the transmission, and

Figure 13 is a wiring diagram of the push button control for operatingthe-valve block, shown in Figure 8, and

ascetic Figure 14 is a view of the push button control used with thistransmission.

Referring to the accompanying drawings, I have used the referencenumeral H] to indicate the housing for my improved transmission. Thehousing In is bolted to the rear face of a torque converter housing IIand a tubular supporting housing I2 is bolted to the rear face of thehousing I0. The forward face of the converter housing II is secured tothe rear end of the vehicle engine in the conventional manner.

I have shown a conventional torque converter installed just ahead of mytransmission but no claim is made that this converter, per se, is partof the invention. It is possible to operate my transmission with aconventional friction clutch interposed between it and the vehicleengine or with a fluid coupling instead of the torque converter shown.However, the gear ratios chosen in the design illustrated were selectedto obtain overall ratios which are the product of the torquemultiplication in the converter and the positive gear ratios in thetransmission. The torque converter selected has a maximum torqueamplification' of about 21 at stall speed and couples up as a fluidcoupling at about 1600 R. P. M.

In order that the complete unit may be better understood, I havedesignated the pump element of the converter by the reference number 13,the turbine element by the numeral 14, and the reactor element by thenumeral !5. The turbine element I4 is splined to the forward end of atransmission drive shaft !6 while the reactor element I is mounted upona stationary sleeve ll through an overrunning clutch 18. The pumpelement l3 extends rearwardly to position adjacent to the transmissionproper and drives an oil pump gear 19 at all times that the engine isoperating.

As has been mentioned, the converter elements .just described are notclaimed to be new or novel,

but have been described to show how the torque converter cooperates withthe transmission to produce the desired overall gear ratios. The onlyimportant function of the converter is to produce a two to one torqueamplification on the shaft l5 for starting which automatically isreduced to one to one when the converter couples up at about 1600 R. P.M.

The drive shaft [6 extends from the torque converter rearwardly into thehousing Hi and terminates in a drive gear 20. A driven shaft 2| extendsrearwardly from the rear end of the drive shaft l6 and projects from thesupport housing [2. The forward end of the driven shaft 2| is providedwith a flange 22 which is fixedly secured to a center web 23 of a planetcarrier 24. The planet carrier 24 serves to rotatably support the'planetpinions which effect the various gear ratios produced by thetransmission.

Equally spaced around the periphery of carrier 24 are three pinions 25each of which is in mesh with the drive gear 22. Only one of thesepinions is shown inthe diagrammatic views 2, 3 and l, as a completeshowing would make it more difiicult to understand the gearing. However,in the actual construction there are three sets of the pinions shownequally spaced around the sun gears. These pinions are 'rotatablymounted upon pins 26 which extend lengthwise through the carrier.Angularly spaced from each of the pins 26 I have provided other pins 27,each of which supports a triple-planet pinion element 28. The triplepinion element 28 is composed of a center pinion 29 which is in meshwith the adjacent pinion 25.

Each triple pinion also comprises a gear 30 and 7s 4 gear 3! locatedrespectively at the forward and rear ends of the triple member. The gear3| is the same size as pinion 29 but the gear 30 is considerably largerthan the gear 29. An intermediate speed sun gear 32 is rotatably mountedupon the drive shaft E6 just. forwardly of the drive gear 20 and is inposition to mesh with each of the gears 30. A low speed sun gear 33 isrotatably mounted on the forward end of the driven shaft 2| justrearwardly of the flange 22 and is in position to mesh with each of thegears 34. A reverse speed internal gear 34 is rotatably mounted on thehub of the gear 33 and extends forwardly in position to mesh with eachof the three gears 3|. Means have been provided for selectively holdingthe gears 32, 33, and 3 3 from rotation to eifect the various speedratios. However, before describing such means it may be well to considerthe gearing employed for each of the speed ratios.

Referring to Figure 2, I have shown the gearing which is employed ineffecting the low-speed ratio. It will be noted from this view that whenthe gear 20 is driven in a clockwise direction and the gear 33 is heldstationary, the carrier 24 is driven forwardly at a reduced speed ratio.When the gear 28 is provided with 21 teeth and thegear 33 provided with27 teeth the carrier is driven in the same direction as the gear 28, onerevolution for each 2.3 revolutions of the gear 20. Thus a 2.3 to 1 lowspeed ratio is obtained.

Referring to Figure 3 it will be noted that when the gear 20 is drivenforwardly and the internal gear 34 is held stationary the carrier 24 isdriven in a reverse direction at a reduced speed. The gear ratioeffected with an internal gear having 63 teeth produces a reverse speedthe ratio of 2.0. The gearing which provides the intermediate speedratio'is shown in Figure 4 from which it will be seen that whenthe sungear 32 is held stationary and the gear 20 is driven forwardly thecarrier 24 will be driven forwardly at a reduced speed. When the sungear 32 is provided with 18 teeth and the pinion 29 and gear 39 areprovided with 18 and 27 teeth, respectively, the carrier will be drivenforwardly one revolution for each 1.57 revolutions of the gear 29. Thusa 1.57 to 1 intermediatespeed ratio is obtained.

From the foregoing it will be seen that to effect the low gear of thetransmission it is only necessary to hold the gear 33 from rotation. Toeffect the reverse speed ratio it is only necessary to hold the internalgear 34 from rotation, and to effect the intermediate speed gear ratioit is only necessary to hold the gear 32 from rotation. The direct driveratio is effected by clutching the gear 32 to the drive shaft it so thatthe gears 32 and 28 must rotate in synchronism. This looks up the entiregear train and of course causes the carrier to rotate with the driveshaft at l to 1 ratio. I

In order to frictionally connect the gear 32 to the drive shaft l6, [Ihave provided a hydraulically operated friction clutch. This clutchcomprises a housing 35 which is keyedto the shaft [6 and in whichhousing a piston 33 is reciprocally mounted. 'The piston 36 is urged toits inoperative position by means of a spring washer 31. Within thehousing 35 I have provided a series of drive discs 38 which are splinedtherein and which discs are all alternated with driven discs 39. Thediscs 39 are splined to a clutch hub40 which is formed integrally withthe gear 32. When fluid under pressure is forced between the housing 35and the piston 36, the discs 38 and 39 will be frictionally forcedtogether to thereby connect the gear 32 to. the. shaft It.

It will be. noted from Figure 4 that. intermediate speed is effectedonly when the sun gear 32 is held from rotation. To. hold this. sun gear32 from rotation I havev provided a sleeve. 4.1 rotatably mounted uponthe hub. iil and a brake drum 42 is fixedly connected to they sleeve.4!. An intermediate speedband 43 is disposed within the housing in aposition to. co-act. with the drum 42. Referring tov Figure 11, it willbe noted that an overrunning brake 44.. is; disposed between the hub 40.and the sleeve 41.. The cam faces of the overrunning brake. are, so.disposed that the hub 40 may rotate. in; the directiongof engine.rotation independently of; the sleeve 41. The overrunning brake permitsthe hub 40 and gear 32 to rotate in a forward direction even when thedrum 42. is helds tationary by band- 43. However, should the forces;onthe gear 22 tend. to rotate this gear in a direction opposite to.engine rotation the brake 14 causes the drum 42 to. be so rotated unlessit is, held stationary by the band 43-. When the drum 42, is. free torotate, then the gear 32; may of; course, rotate in. either direction.

From the foregoing it. will be seen that intermediate. speed ratio iseffected by engaging the band 43 to the drum 42 to. thereby prevent:the. gear 32 from rotating inv a reverse. direction. If new it isdesired to engage the direct drive, it is, only necessary to. engagethe, clutch 35 which connects the gear 372, to, the drive shaft l8. Itshould be noted that when; this clutch is engaged, it is not necessaryto, disengage the band 43. Consequently, power may be cont uously app ehrou h ra smi si during the. transition period from intermediate, pe d.o r i Inasmuc as t e. an 43 normally left engaged. during direct driveonly the clutch 35 need be operated so; that there is no need tosynchronize; the operation of; this clutch with anyother member.

The low speed ratio of the transmission; is effected by holding. thegear 33- frorn. rotation while driving; the gear 30 forwardly. Tovaccomplish this a brake drum s5; is rotatably mounted in; a transmissionend plate 45. The hub of brake drum 45 is splined to-v a sleeve 41 whisis formed integrally with the gear- 33. A low speed band 48, is disposedwithin the housing I0 in position to co-act with the drum 45; and thushold the gear 33-from rotation.

To effect the reverse speed, ratioof the transmission, it is onlynecessary to hold the internal gear 34 from rotation. The gear 3,4,isprovided with a hub 49 which is rotatably mounted upon the sleeve 4?. Areverse speed brake band 591 is positioned within the housing to co-actwith the periphery of the. gear 34. Asis; characteristic of all reversegear ratios, the torque which must be withheld by the reverse speed;band is a product of the engine torque and the gear detrimental lateraldeflection, of the gear set,

due to this side thrust, an annular boss. 5,!" is provided in thehousing It which closely. fits the periphery of the gear 34,;just;rearwardly of the reverse band 50. There is suflicient clearance betweenthe boss 51- andthe gear 34.- that in neutral. and. in all forwardspeeds the. gear 34 is free torotate. However, when the reverse speedband is applied and the transmission isplaced under load, the force.which tends to rotate the band around its; anchor-is resisted by theboss 51.. Under this conditionv there is no rotation between the gear34. and. the boss. 51: so. that. the boss simply acts as. a support andnot as; a bearing.

It; will be. noted that. in neutral position where all of the bands are.free from their respective drums. and the planetarylockup clutch 35; isout. of engagement, rotation of the, drive. shaft it simply rotates thegear 32 and brake. drum as. in a reverse direction. When: the. reversespeed ratio; is. engaged the gear- 32; is; likewise rotated; in. areverse. direction: relative to. the drive shaft 15;. When the low.speed ratio. is engaged the gear 32 is. also. rotated in; a.reverse'direction but at; a somewhat; slower speed relative, to the gear2o. When intermediate speedratio. is en.- gaged the gear 32 isheld from.rotation, In direct drive the gear 20 is; coupled; to. the gear 32 sothat. the two gears rotate. synchronism with each. other. Consequently,the ear; 32 in all of the various, speeds, (i. e.. neutral, reverse,low, intermediate, and direct, drive) is never, called. upon to rotate,faster than the, drive. shaft: I6.

I have made use of thischaracteristic of this particular. gearing. to.provide. a. direct; drive from. the driven shaft, 2| to the. drive shaftI6 when the transmission is. in neutral position. To. accomplish this,an. OVerrunningclutch: is inserted between, the. gear 32 and theshaft:16 which prevents the gear 32 from over-running the gear 29. Thisconstruction is shown in Figure 1.0. from which it will be. noted thatone element. of an overrunning clutch unit 52 is. mounted within theforward portion. of the clutch hub. 40. while the other element 5.3. ofthe overrunning. clutch- 2 is keyed to shaft. I'B.. The cam. faces onthis overrunning clutch. are so disposed. that. the. hub 40 cannot.overrun theshaft I6. ina forward direction. The function-ofthisoverrunning. clutch is that when. power is applied. to the drivenshaft 2| in. av forward. direction. the. gear 32' will tend to, overrunthe. gear 20. in a forward direction. The overrunning clutch 52 preventsthis overruns ning and; locks up. the gear. set against such roe tation.Thus theengine of the, car-maybestarted in neutral position simply bypushing the: car forward.v This feature also prevents freewheelingofthetransmission on down; gradessothat in any speed the engine isavailable as; a brake. A unique feature of this transmission is thatwhen descending a grade with the; engine being used asa brake, the lowspeed band may be engaged for more effective braking withoutfirst;bringing the. car; to a stop. Thisis characteristic of mytransmissionand makes it; unnecessary taprovide a wheel. driven oil pumpv to;operate any; of the bands or clutchesto startthe engine byspushs ing;thecar;

Figures v5, 6 and '7. illustrate the hydraulicallyoperatecl mechanismfor'applying'the. bands 43'. audit to their respectiveidrumsr It will;be noted from these. views that. the.- housing i0. is. provided" withfour'bosses; 5'3, whichv extend inwardly from the-bottom face ofthehousingand to which bosses are secureda plate.:5.4..

screws 55 rigidlysecure. thi plate; in position, Referring to- Figure 5,it willbenoted thatl have provided a low speed; cylinder- 56 which; is,cast: inte ral y with the p at 5 ,111 wh ch. cy nder 56;. and a piston514s reciprooably mounted. An arm? Four, cap:

=erative positions. sure is applied to the cylinder 56 the piston 51 bymeans of a piston rod 59.

The energized end of the low speed brake band 48 is anchored againstrotation by means of a pin 66 while the opposite end of the band 48 isconnected to the arm 50 by a link 6|. A spring 62 urges the arm 48 andpiston to their inop- Thus, when fluid under preswill be forcedoutwardly to thus rotate the arm 58 and apply the brake band 48 to thelow speed drum 45.

An intermediate speed brake operating cylinder 63 is also castintegrally with the plate 54 but in alignment with the intermediatespeed brake band 43. The piston and operating mechanism associated withthis cylinder have not been illustrated in detail because they aresubstantially the same as the low speed brake operating mechanism, justdescribed. 7

A reverse speed operating mechanism is illustrated in Figure 6 fromwhich it will be seen that a relatively large cylinder 64 is detachablysecured to the underside of the plate 54, which cylinder is providedwith a piston 65 which rotates an arm 66 through a connecting rod 6?.The arm 66 is connected to the reverse band 55 by a link 68. Thus, whenfluid is applied to the piston 65 the arm 66 will be rotated to applythe band 56 to the reverse gear 36. V

In assembling the hydraulic operating mechanism it is only necessary tofasten the cylinder 64 to the bottom of the plate 56 and install thevarious connecting rods and arms. The plate 54 may then be bolted inposition to the underside of the housing [0 and the links BI and 66 andthe intermediate speed link inserted to complete 'the assembly. Suitableadjusting devices areprovided for each of the bands, as is customary inthis type of mechanism.

Solenoid operated valves are provided for controlling the variouspistons and direct drive clutch, but it should be kept in mind thatmechanically operated valves may be substituted if itis desired tooperate the transmission in such manner. However, in the solenoidoperated valves shown, a valve block 69 is secured to one side of thehousing [6, which valve block is provided with four piston type balancedvalves. These valves are all numbered 10. The upper end of each valve isformed integrally with a solenoid plunger ll. Each plunger H andassociated valve 75 is urged to its inoperative position by means of aspring 12. A solenoid coil 3 is disposed around each plunger H, whichwhen energized draws the plunger 7| upwardly against the resistance ofthe spring 12 to open the particular valve 76 associated therewith Asuitable port 14 is drilled in the housing [0 which inder and when thesolenoid is deenergized, the

cylinder is connected to the discharge port that the fluid therein mayreadily flow to the sump of the transmission. A suitable oil pan 16 isdetachably secured "to the lower face of the housing in position toenclose the plate 64 and all of the operating mechanism. Although all ofthe solenoid valves are identical I have numbered the valves used toefiect the direct drive, the intermediate speed, the low speed, and thereverse speed by numerals 66, SI, 62 and 83, respectively. With the formof control shown, I have provided four position buttons on theinstrument panel. These may be conveniently marked with N for neutral, Ffor forward, L for low and R for reverse. The F, L, and R buttonsoperate switches which control the intermediate speed, low and reversespeed solenoids, respectively. The switches are arranged so that whenany one button is pressed any other button that is at that time engagedwill be thrown out. The neutral button is provided so that whendepressed any other button which is engaged will be thrown out.

' The low, reverse, and intermediate speed gear ratios are engagedmanually by pressing the respective buttons but the planetary lockupclutch is engaged automatically. Any one of several well-known torqueand speed-responsive mechanisms is suitable for engaging the plane tarylockup clutch. In the control selected a vacuum-operated switch 11 isprovided which opens a circuit through the direct drive solenoid 86 whenthe vacuum in the engine manifold is reduced below a predeterminedvalue. This switch is connected in series with the push button F asshown in Figure 13. A second switch 18 is arranged to by-pass the switch11, the switch 18 being operated by a governor 19.

The switch operated by the N button is connected in series with astarter switch 64 and starter relay 85. Thus the engine can be crankedby the starter only when in neutral position.

In the normal operation of the transmission in a forward direction, theF button is depressed and the engine accelerated. The vacuum in theintake manifold will drop under these conditions to open the switch T2.The switch 77 will thereby break the circuit with the direct drivesolenoid 80 to thereby disengage the planetary lockup clutch. Theintermediate speed band 43 however will remain engaged so that thetransmission under these conditions will operate in intermediate speed.If new the vacuum in the intake manifold raises above the predeterminedvalue or the governor 18 attains a predetermined speed, either of theswitches 71 or 18 will be closed to thereby engage the planetary lockupclutch 35. If the speed of the governor is maintained above thatcorresponding to about 50 miles per hour, operation of the vacuum switch17 will have no effect in disengaging the planetary lockup clutch.However, should the car speed be lower than 50 miles per hour and thethrottle of the engine is suddenly opened, the vacuum in the manifoldwill immediately drop on and de-energize the planetary lockup clutchsolenoid to place the transmission in intermediate speed ratio. However,as soon as the vacuum again increases, the planetary lockup clutch willbe engaged to again place the transmission in direct drive.

Due to the fact that a 2 to 1 torque amplification is obtained in theconverter, all normal starting in a forward direction may be obtained inintermediate speed. This provides an overall ratio of over 3 to 1. Thispermits the converter to quickly reach engine speed while still operatmgunder a 1.57 to 1 ratio. The low and reverse speed ratios are manuallyengaged because they are only used occasionally.

Among the many advantages arising from the use of my improvedtransmission it may be well to mention that I have provided atransmission having three forward speeds and one reverse speed in whichthe driving shaft and the driven shaft are connected to each other ateach particular gear ratio by the operation of a single control memberand in which the transition from intermediate speed to direct drive isaccomplished by the engagement of a single clutch without the release ofany other member. Thus, synchronization and its associated troubles areavoided in this transmission.

Still a further advantage obtained with this transmission is that a 1 to1 drive from the driven shaft to the driveshaft is obtained in neutralposition to thus make it unnecessary to operate any band or clutch whenthe engine is to be started by pushing the car.

Some changes may be made in the arrangement, construction, andcombination of the various parts provided in my improved transmissionwithout departing from the spirit of my invention and it is my intentionto cover by my claims such changes as may reasonably be included withinthe scope thereof.

I claim as my invention:

1. In a variable speed mechanism for a motor vehicle, in combination, anengine, variable speed gearing driven by said engine, brake meansarranged when applied to shift said Variable speed gearing to apredetermined speed reduction, a solenoid operated valve controllingsaid brake means, clutch means arranged when engaged and said brakemeans are applied to shift said variable speed gearing into directdrive, a second solenoid operated valve controlling said clutch means, amanually operated switch, said first and second solenoids being arrangedin parallel with each other and in the circuit of said manually operatedswitch, a vacuum controlled switch and a speed responsive switcharranged in parallel with each other and in the branch circuit of saidsecond solenoid so that the variable speed gearing operates in saidspeed reduction when both the engine vacuum and vehicle speed are belowpredetermined values and in direct drive when either engine vacuum orthe vehicle speed are above predetermined values.

2. In a variable speed transmission for a motor vehicle, in combination,an engine, variable speed gearing driven by said engine, brake meansassociated with said gearing and arranged when applied to condition saidgearing to transmit torque at a predetermined speed reduction, fluidpressure means for applying said brake means, a solenoid operated valvecontrolling th fiuid pressure means for said brake means, clutch meansassociated with said gearing and arranged when engaged and said brakemeans are applied to condition said gearing to transmit torque in directdrive, fluid pressure means for engaging said clutch means, a secondsolenoid operated valve controlling the iiuid pressure means for saidclutch means, a source of electrical power arranged to energize saidfirst and second solenoids, a manually operated switch common to thecircuits of said first and second solenoids, a speed responsive switchin the circuit of said first solenoid only and a vacuum controlledswitch in parallel with said speed responsive switch so that the circuitthrough said first solenoid will be completed whenever either thevehicle speed or the engine vacuum exceeds their respectivepredetermined values thereby placing said transmission in direct drive.

EDWIN C. McRAE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,251,625 Hale Aug. 5, 19412,281,916 Claytor May 5, 1942 2,366,253 Griswold Jan. 2, 1945 2,366,254Paton Jan. 2, 19 5

